The Create a Decimal Calculation Action Builder will perform a designate calculation and return a decimal value.

Enter in the calculation and click Next.

Values can be passed into Calculation by creating a parameter.
By enclosing a value in [ ] brackets, that flags the word as a parameter. The name of the parameter, in the picture, would be statename.
Parameters will have the value substituted during the script execution.

If parameters are found in the Calculation, they wil be listed in the Name drop down.
Name – the name of the parameter within the criteria.
Type – type of value to be expected (String, Bool, Date, Decimal, Number).
Variable – the variable that will hold the value. The drop down will contain existing variables or type in a new variable name.
Click the Add button to add the parameter name and value to be substituted.

Created Script

Add Text Calc Parameter – maps a Calculation Parameter to a value to be substituted.
Decimal Calculation – performs a calculation and returns a Decimal value.
Note: all Parameter variables will need to be set prior to this portion of the script.